MRI characterization of 124 CT-indeterminate focal hepatic lesions: evaluation of clinical utility.

OBJECTIVE To evaluate the diagnostic yield of MRI performed for characterization of focal hepatic lesions that are interpreted as indeterminate on CT. PATIENTS AND METHODS In a retrospective investigation, 124 indeterminate focal hepatic lesions in 96 patients were identified on CT examinations over 5 years from 1997 to 2001. All patients had MRI performed for the liver within 6 weeks of their CT examination. CT and MR images were reviewed independently by two separate groups of two radiologists. The value of MRI in characterizing these lesions was assessed. Diagnoses were confirmed based on histology, characteristic imaging features, and clinical follow-up. RESULTS MRI definitely characterized 73 lesions (58%) that were indeterminate on CT. MRI was accurate in 72/73 of these lesions. MRI could not definitely characterize 51 lesions (42%). Ten lesions were not visualized on MRI, and follow-up imaging confirmed that no lesion was present in eight of these cases (pseudolesions). CONCLUSION MRI is valuable for the characterization of indeterminate focal hepatic lesions detected on CT.